What does highpoly mesh shrinkwrapped to lowpoly mesh aimed for?
A subdivided Low Poly creates a smooth curve, the more control points you have, the more they have to be manually trimmed.
Probably he wanted to adjust and smooth a curve overriding errors of maual adjustements.
In my example both meshes are the same, with 6 vertices only, one subdivided and one straight. The subdivided one creates a smooth curve.